With rapid increasing in requirement of radio communication globally, various network providers focus on reconfigurable radio systems (RRS). RRS is a comprehensive concept. A RRS solution is based on, for example, a soft reconfiguration and cognitive radio technique by radio application. It aims at an ability to develop reconfiguration radio and develop a network adapted to an environment varying dynamically. In an aspect, RRS may be simply described as follows. To realize maximum spectrum resource utilization, under the premises of ensuring usage of spectrum of a primary system of a communication system, spectrum resources are allocated to a secondary system included in the communication system using a dynamic spectrum management manner. RRS can increase spectrum utilization significantly.
CR is an intelligent communication system which is perceptible of external communication environment. Briefly speaking, to increase spectrum utilization, a wireless communication device with cognitive capability may operate in a frequency band that has been authorized to another communication system in a certain “opportunistic” manner. Practically, this is possible only when the authorized frequency band has not been utilized or only a few communication services are active in the authorized frequency band. The available spectrum resources occurring in space domain, time domain and frequency domain is referred to as a “spectrum hole”. A core concept of the CR is to enable the wireless communication device to have an ability to discover and utilize reasonably the “spectrum hole”.
Nowadays, a critical technique for achieving the CR is a center server, such as a geolocation database (GLDB). Based on the protection requirement of the primary system and a geolocation of the secondary system which requests to utilize the spectrum resources, available spectrum resources, such as the available frequency band or the maximum transmission power, of the secondary system is calculated. The secondary system utilizes the spectrum resources in the authorization range of the GLDB, thereby reducing the requirement on the cognitive capability of the secondary system itself, and achieving opportunistic access of the secondary system while ensuring a normal operation of the primary system.
As another technique aiming to meet the requirement of the mobile communication system of high speed, large capacity, and reliable transmission, a multi-antenna (MIMO) system is also researched widely. Researches shows that, the MIMO system can provide larger capacity than the conventional single-antenna system, and the capacity of the MIMO system increases linearly with the number of antennas.
However, current CA is in an initial stage. A researcher generally pays attention to how to protect the primary system but neglect the communication quality requirement of the secondary system in a case where the spectrum resources are utilized opportunistically. In this context, the inventor of the disclosure provides prospectively how to achieve the efficiency utilization of the spectrum resources, which have been authorized to the primary system, by the secondary system based on the feature of the MIMO system.